Mind hand skill
A advanced handicraft subskill v5c2
"After achieving a near-legendary level of dexterity, you can summon a “third hand” using your mind. Using the “third hand”, it is possible to manipulate objects and even attack enemies."
"However, it is not possible for your “third hand” to use any skills. Mana consumption per second: 2"
Mana using skill
It was said that it could not be directly used in combat. But it an be used to parry or disturb someone else movement (source, may be in Jigolath, against the leader of the chaos warrior)